Arabidopsis plants perform arithmetic division to prevent starvation at night

Scialdone, Antonio; Mugford, Sam T.; Feike, Doreen; Skeffington, Alastair; Borrill, Philippa; Graf, Alexander; Smith, Alison M.; Howard, Martin

doi:10.7554/elife.00669

Cited by 148 publications

(274 citation statements)

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“…Both enzymes are required for normal rates of starch degradation. Intriguingly, the level of phosphorylation of the starch granule (measured as the 6-phosphate content per unit Glc) increases markedly during the light period then falls at night (Scialdone et al, 2013). This pattern potentially generates a diel change in the accessibility of the granule surface to hydrolytic enzymes; hence, it might account for the increased propensity for starch degradation with time in the light.…”

Section: Starch Turnover In Long Days and In Twilight May Reflect An mentioning

confidence: 99%

“…The increasing propensity for starch degradation with time in the light is reminiscent of the fact that the rate of starch degradation following the onset of darkness increases with time after dawn (Graf et al, 2010;Scialdone et al, 2013). It is pertinent to ask whether these phenomena are related.…”

Section: Starch Turnover In Long Days and In Twilight May Reflect An mentioning

confidence: 99%

“…An alternative explanation is that the propensity for starch degradation in the light increases as a direct function of time after dawn, under the control of the circadian clock or another endogenous timing mechanism. We showed previously that the circadian clock determines the rate of starch degradation at night (Graf et al, 2010;Scialdone et al, 2013). At the onset of darkness, information about time remaining until dawn, derived from the clock, is integrated with information about starch content to set a constant rate of degradation that will result in the consumption of almost all of the stored starch by dawn.…”

Section: Starch Turnover In Long Days and In Twilight May Reflect An mentioning

confidence: 99%

“…Both mutants have altered diel patterns of primary carbohydrate metabolism. The cca1 lhy mutant degrades starch too quickly during the night, so that starch reserves are exhausted before dawn (Graf et al, 2010;Scialdone et al, 2013). The prr7 prr9 mutant maintains a higher ratio of starch to Suc synthesis during the day than wild-type plants (Kölling et al, 2015a On the day of the experiment, starting at dawn, plants were transferred to continuous light.…”

Section: The Onset Of Starch Degradation In Continuous Light Is Influmentioning

confidence: 99%

“…The clock is already known to play a central role in starch metabolism, in that it controls the rate of starch degradation during the night (Graf et al, 2010;Graf and Smith, 2011;Scialdone et al, 2013). To establish whether then transferred at dawn to continuous light at 105 (upper data set) or 65 (lower data set) mmol quanta m 22 s 21 .…”

Section: The Onset Of Starch Degradation In Continuous Light Is Influmentioning

confidence: 99%

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Leaf Starch Turnover Occurs in Long Days and in Falling Light at the End of the Day

et al. 2017

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Section: Starch Turnover In Long Days and In Twilight May Reflect An mentioning

confidence: 99%

Section: Starch Turnover In Long Days and In Twilight May Reflect An mentioning

confidence: 99%

Section: Starch Turnover In Long Days and In Twilight May Reflect An mentioning

confidence: 99%

Section: The Onset Of Starch Degradation In Continuous Light Is Influmentioning

confidence: 99%

Section: The Onset Of Starch Degradation In Continuous Light Is Influmentioning

confidence: 99%

See 3 more Smart Citations

Leaf Starch Turnover Occurs in Long Days and in Falling Light at the End of the Day

et al. 2017

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Temporal Control of Plant–Environment Interactions by the Circadian Clock

Haydon

Ting

2019

Annual Plant Reviews Online

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The rotation of the earth generates dramatic daily and seasonal variation in the terrestrial environment. Plants, like other organisms, have evolved an endogenous biological oscillator to predict these daily changes in light and temperature and adjust to shifting seasonal conditions. This system must be robust to unexpected environmental challenges but can also assist plants to adjust physiology accordingly. Key features of the circadian system which contribute to achieve these are the process of entrainment, by which external cues adjust the state of the oscillator, and gating, by which the sensitivity to a stimulus is modified according to the time of day. In this way, the circadian clock is a dynamic hub which integrates physiology, metabolism and growth in the context of a plant's current environment. We provide a comprehensive summary of the molecular composition of the core oscillator in Arabidopsis and the mechanisms of entrainment and gating. In particular, we focus on phytohormone signalling, photosynthetic metabolism and defense responses as examples of core plant responses to environment that are integrated within the circadian system. We are grateful for financial support from the University of Melbourne.

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Feedback regulation by trehalose 6‐phosphate slows down starch mobilization below the rate that would exhaust starch reserves at dawn in Arabidopsis leaves

et al. 2018

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Trehalose 6-phosphate (Tre6P), a sucrose signaling metabolite, inhibits transitory starch breakdown in Arabidopsis (Arabidopsis thaliana) leaves and potentially links starch turnover to leaf sucrose status and demand from sink organs (Plant Physiology, 163, 2013, 1142. To investigate this relationship further, we compared diel patterns of starch turnover in ethanol-inducible Tre6P synthase (iTPS) lines, which have high Tre6P and low sucrose after induction, with those in sweet11;12 sucrose export mutants, which accumulate sucrose in their leaves and were predicted to have high Tre6P. Short-term changes in irradiance were used to investigate whether the strength of inhibition by Tre6P depends on starch levels. sweet11;12 mutants had twofold higher levels of Tre6P and restricted starch mobilization. The relationship between Tre6P and starch mobilization was recapitulated in iTPS lines, pointing to a dominant role for Tre6P in feedback regulation of starch mobilization. Tre6P restricted mobilization across a wide range of conditions. However, there was no correlation between the level of Tre6P and the absolute rate of starch mobilization.Rather, Tre6P depressed the rate of mobilization below that required to exhaust starch at dawn, leading to incomplete use of starch. It is discussed how Tre6P interacts with the clock to set the rate of starch mobilization. K E Y W O R D SArabidopsis, circadian clock, diel, starch, trehalose 6-phosphate | INTRODUCTIONPlants use light energy to drive photosynthetic carbon (C) gain, metabolism, and growth, but at night depend on C reserves accumulated in previous light periods. In many species, including Arabidopsis, foliar starch is the major C reserve (Smith & Stitt, 2007). Diel regulation of starch turnover may depend on the conditions (Paul & Foyer, 2001). In source-limited plants, C is in short supply and it is crucial to manage C reserves to insure rapid investment in growth while avoiding C starvation at night (Scialdone and Howard, 2015;Smith & Stitt, 2007;Stitt & Zeeman, 2012). In sink-limited conditions, C regulation of metabolism and growth is relaxed (Baerenfaller et al., 2015;Sulpice et al., 2014) and starch often accumulates in leaves and other parts of the plant. This incomplete utilization of starch may be at least partly due to feedback inhibition of starch mobilization by the sucrose signal trehalose 6-phosphate (Figueroa Lunn, Delorge, Figueroa, Van Dijck, & Stitt, 2014;Martins et al., 2013). The following experiments provide further evidence that Tre6P plays a key role in the feedback regulation of starch mobilization. In particular, we ask whether feedback inhibition by Tre6P is minimized to allow full use of starch in conditions where C is in short supply, but operates effectively when C is in excess.When Arabidopsis plants grow in conditions where less C is available per 24 hr cycle, they accumulate a larger proportion of their fixed C to starch in the daytime and slow down mobilization of starch during the night, compared to plants growing with a larg...

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Arabidopsis plants perform arithmetic division to prevent starvation at night

Cited by 148 publications

References 30 publications

Leaf Starch Turnover Occurs in Long Days and in Falling Light at the End of the Day

Leaf Starch Turnover Occurs in Long Days and in Falling Light at the End of the Day

Temporal Control of Plant–Environment Interactions by the Circadian Clock

Feedback regulation by trehalose 6‐phosphate slows down starch mobilization below the rate that would exhaust starch reserves at dawn in Arabidopsis leaves

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